This invention relates to a process for the preparation of staple fibers with high strength and high tensile modulus. More specifically, this invention relates to a process for the preparation of polybenzazole staple fibers.
Staple fibers are short, random fibers or filaments which are typically prepared by cutting a dried fiber or filament into short lengths. Such fibers are particularly useful in composite applications. It is known to prepare filaments and fibers of polybenzazole polymers by extrusion of a solution of the polymer, followed by drawing, washing, and drying of the extrudates. It is also known to prepare short polybenzazole fibers by cutting the filament after it has been washed and while it is still wet, as described in U.S. Pat. No. 5,164,131. However, filaments which have been thoroughly washed are rigid and difficult to cut while traveling at a high line speed. Accordingly, it would be desirable to develop an improved process for the preparation of cut fibers.